海岸带生物学与生物资源保护实验室知识库

甲壳素，主要来源于虾、蟹壳等，是自然界中储量仅次于纤维素的第二大多糖资源。壳聚糖，作为一种最重要的甲壳素衍生物，是甲壳素部分或完全脱乙酰化而得到的高分子化合物。壳聚糖是一种天然、可再生的生物资源，具有可降解性和良好的生物相容性，在农业、医药、日化、食品、环保等领域得到了广泛的关注。但是，壳聚糖难溶于水，生物活性较差，很大程度上限制了它的工业化开发。化学改性被认为是一种高效、定向、方便的方法，能够提高甚至赋予化合物新的功能从而满足不同的需求。因此，对壳聚糖进行化学修饰，从而提高其水溶性和生物活性，将有利于更加全面地开发这种丰富的多糖资源。

论文以壳聚糖为修饰对象，以制备具有优良活性的壳聚糖水溶性衍生物为目标，基于离子交换的思想，分别将卤代乙酸阴离子、羟基酸阴离子、羧基多糖阴离子引入2-羟丙基三甲基铵类壳聚糖中，得到17种不同阴离子化2-羟丙基三甲基铵类壳聚糖。通过红外光谱、核磁共振谱以及元素分析等方法对产物的结构进行鉴定，通过抑菌、抗氧化、吸湿保湿实验，重点分析了不同阴离子对2-羟丙基三甲基铵类壳聚糖活性及性能的影响。

为了进一步增强壳聚糖的抑菌活性，实验将具有潜在抑菌功能的卤素基团引入2-羟丙基三甲基铵类壳聚糖。通过红外吸收光谱法、核磁共振波谱法以及元素分析等方法表征了衍生物的结构。然后采用菌丝生长速率法测试了衍生物对灰葡萄孢病菌、黄瓜枯萎致病菌、芦笋茎枯致病菌及西瓜枯萎致病菌的体外抗菌活性。结果表明，卤素基团的引入显著提高了壳聚糖的抑菌活性。

为了提高壳聚糖的抗氧化活性，实验将具有潜在抗氧化活性的羟基酸，包括香豆酸、阿魏酸、对香豆酸、水杨酸、抗坏血酸、没食子酸、咖啡酸、对羟基苯甲酸等分别引入2-羟丙基三甲基铵类壳聚糖中，得到了一系列衍生物，并对其进行了结构鉴定和抗氧化活性测试（清除羟基自由基、DPPH自由基、超氧阴离子自由基）。结果表明，羟基酸阴离子的引入显著地提高了壳聚糖的抗氧化活性。

为了提高壳聚糖的吸湿保湿性能，将亲水性的羧基多糖阴离子接到2-羟丙基三甲基铵类壳聚糖中，制备了3种不同的含羧甲基多糖阴离子的2-羟丙基三甲基铵类壳聚糖，并对其分别进行了吸湿、保湿性能测试。结果表明，将羧基多糖阴离子引入2-羟丙基三甲基铵类壳聚糖后，产物的吸湿、保湿性能显著提高。

论文提供了具有不同活性的阴离子化2-羟丙基三甲基铵类壳聚糖的制备方法，并比较系统地研究了不同阴离子对2-羟丙基三甲基铵类壳聚糖的活性及性能影响，为壳聚糖在农业、医药、日化等领域的进一步开发提供了新思路。
 

Chitin, mainly derived from shrimp and crab shells, is the second largest polysaccharide resource in nature with only less reserves than cellulose. Chitosan, as one of the most important derivatives of chitin, is a macromolecule compound obtained by partial or complete deacetylation of chitin. Chitosan is a natural and renewable biological resource with good biocompatibility and biodegradability, which attracts broad attention in such areas as agriculture, medicine， daily chemicals, food, environmental protection etc. However, the insoluble ability of chitosan in water and the insufficiency of some biological activities greatly limit its further industrial development. Chemical modification is considered to be an efficient, targeted and convenient method, which can improve or even give new functions to polysaccharides to meet different needs. As a result, the chemical modification of chitosan to improve its water solubility as well as biological activity will be conducive to the more comprehensive development of this rich polysaccharide resources.
The aim of this paper is to prepare chitosan derivatives with good water solubility and excellent activity. Based on ion exchange, the anions of halogenated acetic acid, hydroxy acid and carboxyl polysaccharide were introduced into 2-hydroxypropyl trimethylammonium chitosan respectively. Finally, 17 kinds of anionic 2-hydroxypropyl trimethylammonium chitosan were obtained. And the datailled chemical structures of these chitosan derivatives were characterized by means of FTIR, 1H NMR, 13C NMR, as well as elemental analysis. We emphatically studied the effects of different anions on the bioactivity of 2-hydroxypropyl trimethylammonium chloride chitosan.
In order to improve the antifungal activity of chitosan, halogen groups with potential antifungal activity were introduced into 2-hydroxypropyl trimethylammonium chloride chitosan. The structures of the derivatives were characterized by FTIR, NMR, and elemental analysis. Their antifungal activity against Botrytis cinerea, Fusarium oxysporum f. sp. cucumerium Owen, Fusarium oxysporum f. sp. Niveum, and Phomopsis asparagi were studied in vitro by mycelium growth rate method. The results revealed that the halogen groups significantly increased the antifungal activity of chitosan.
In order to improve the antioxidant activity of chitosan, organic acids with potential antioxidant activity, including coumaric acid, ferulic acid, p-coumaric acid, salicylic acid, ascorbic acid, gallic acid, caffeic acid and p-hydroxybenzoic acid, were introduced into 2-hydroxypropyl trimethylammonium chloride chitosan to obtain a series of chitosan derivatives. Structures identification and the evaluation of antioxidant activity, including hydroxyl radicals scavenging activity, DPPH radicals scavenging activity, and superoxide radicals scavenging activity were carried out subsequently. The results showed that the antioxidant activity of chitosan was significantly enhanced by the introduction of organic acid salts.
In order to improve the hygroscopic and moisturizing activity of chitosan, the hydrophilic carboxyl polysaccharides were introduced into 2-hydroxypropyl trimethylammonium chloride chitosan to obtain three different 2-hydroxypropyl trimethylammonium chloride chitosan - carboxylic polysaccharide complex salts. The hygroscopic and moisturizing activity were tested respectively. Results showed that the hygroscopic and moisturizing activity of chitosan derivatives were enhanced significantly.
In this paper, the preparation of chitosan derivatives with antibacterial activity, antioxidant activity, and hygroscopic and moisturizing activity were provided. The effects of different anions on the bioactivity of 2-hydroxypropyl trimethylammonium chloride chitosan were systematically studied, which provided a new idea for the further development of chitosan in the fields of medicine and cosmetic.